Show that the expansion of does not contain any term involving x 9 .

Question

Philoid · Accepted Answer

For ,

a=2x², and n=20

We have a formula,

To get coefficient of x⁹ we must have,

(x)^40-3r = (x)⁹

• 40 - 3r = 9

• 3r = 31

• r = 10.3333

As is not possible

Therefore, the term containing x⁹ does not exist in the expansion of

Show that the expansion of does not contain any term involving x9.